clocksource: SuperH TMU Timer driver

This patch adds a TMU driver for the SuperH architecture.

The TMU driver is a platform driver with early platform
support to allow using a TMU channel as clockevent or
clocksource during system bootup or later.

Clocksource or clockevent can be selected.
Both periodic and oneshot clockevents are supported.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 461 insertions, 0 deletions

diff --git a/drivers/clocksource/sh_tmu.c b/drivers/clocksource/sh_tmu.c
new file mode 100644
index 00000000000..21bd77aa6a3
--- /dev/null
+++ b/drivers/clocksource/sh_tmu.c
@@ -0,0 +1,461 @@
+/*
+ * SuperH Timer Support - TMU
+ *
+ *  Copyright (C) 2009 Magnus Damm
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/irq.h>
+#include <linux/err.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/sh_tmu.h>
+
+struct sh_tmu_priv {
+	void __iomem *mapbase;
+	struct clk *clk;
+	struct irqaction irqaction;
+	struct platform_device *pdev;
+	unsigned long rate;
+	unsigned long periodic;
+	struct clock_event_device ced;
+	struct clocksource cs;
+};
+
+static DEFINE_SPINLOCK(sh_tmu_lock);
+
+#define TSTR -1 /* shared register */
+#define TCOR  0 /* channel register */
+#define TCNT 1 /* channel register */
+#define TCR 2 /* channel register */
+
+static inline unsigned long sh_tmu_read(struct sh_tmu_priv *p, int reg_nr)
+{
+	struct sh_tmu_config *cfg = p->pdev->dev.platform_data;
+	void __iomem *base = p->mapbase;
+	unsigned long offs;
+
+	if (reg_nr == TSTR)
+		return ioread8(base - cfg->channel_offset);
+
+	offs = reg_nr << 2;
+
+	if (reg_nr == TCR)
+		return ioread16(base + offs);
+	else
+		return ioread32(base + offs);
+}
+
+static inline void sh_tmu_write(struct sh_tmu_priv *p, int reg_nr,
+				unsigned long value)
+{
+	struct sh_tmu_config *cfg = p->pdev->dev.platform_data;
+	void __iomem *base = p->mapbase;
+	unsigned long offs;
+
+	if (reg_nr == TSTR) {
+		iowrite8(value, base - cfg->channel_offset);
+		return;
+	}
+
+	offs = reg_nr << 2;
+
+	if (reg_nr == TCR)
+		iowrite16(value, base + offs);
+	else
+		iowrite32(value, base + offs);
+}
+
+static void sh_tmu_start_stop_ch(struct sh_tmu_priv *p, int start)
+{
+	struct sh_tmu_config *cfg = p->pdev->dev.platform_data;
+	unsigned long flags, value;
+
+	/* start stop register shared by multiple timer channels */
+	spin_lock_irqsave(&sh_tmu_lock, flags);
+	value = sh_tmu_read(p, TSTR);
+
+	if (start)
+		value |= 1 << cfg->timer_bit;
+	else
+		value &= ~(1 << cfg->timer_bit);
+
+	sh_tmu_write(p, TSTR, value);
+	spin_unlock_irqrestore(&sh_tmu_lock, flags);
+}
+
+static int sh_tmu_enable(struct sh_tmu_priv *p)
+{
+	struct sh_tmu_config *cfg = p->pdev->dev.platform_data;
+	int ret;
+
+	/* enable clock */
+	ret = clk_enable(p->clk);
+	if (ret) {
+		pr_err("sh_tmu: cannot enable clock \"%s\"\n", cfg->clk);
+		return ret;
+	}
+
+	/* make sure channel is disabled */
+	sh_tmu_start_stop_ch(p, 0);
+
+	/* maximum timeout */
+	sh_tmu_write(p, TCOR, 0xffffffff);
+	sh_tmu_write(p, TCNT, 0xffffffff);
+
+	/* configure channel to parent clock / 4, irq off */
+	p->rate = clk_get_rate(p->clk) / 4;
+	sh_tmu_write(p, TCR, 0x0000);
+
+	/* enable channel */
+	sh_tmu_start_stop_ch(p, 1);
+
+	return 0;
+}
+
+static void sh_tmu_disable(struct sh_tmu_priv *p)
+{
+	/* disable channel */
+	sh_tmu_start_stop_ch(p, 0);
+
+	/* stop clock */
+	clk_disable(p->clk);
+}
+
+static void sh_tmu_set_next(struct sh_tmu_priv *p, unsigned long delta,
+			    int periodic)
+{
+	/* stop timer */
+	sh_tmu_start_stop_ch(p, 0);
+
+	/* acknowledge interrupt */
+	sh_tmu_read(p, TCR);
+
+	/* enable interrupt */
+	sh_tmu_write(p, TCR, 0x0020);
+
+	/* reload delta value in case of periodic timer */
+	if (periodic)
+		sh_tmu_write(p, TCOR, delta);
+	else
+		sh_tmu_write(p, TCOR, 0);
+
+	sh_tmu_write(p, TCNT, delta);
+
+	/* start timer */
+	sh_tmu_start_stop_ch(p, 1);
+}
+
+static irqreturn_t sh_tmu_interrupt(int irq, void *dev_id)
+{
+	struct sh_tmu_priv *p = dev_id;
+
+	/* disable or acknowledge interrupt */
+	if (p->ced.mode == CLOCK_EVT_MODE_ONESHOT)
+		sh_tmu_write(p, TCR, 0x0000);
+	else
+		sh_tmu_write(p, TCR, 0x0020);
+
+	/* notify clockevent layer */
+	p->ced.event_handler(&p->ced);
+	return IRQ_HANDLED;
+}
+
+static struct sh_tmu_priv *cs_to_sh_tmu(struct clocksource *cs)
+{
+	return container_of(cs, struct sh_tmu_priv, cs);
+}
+
+static cycle_t sh_tmu_clocksource_read(struct clocksource *cs)
+{
+	struct sh_tmu_priv *p = cs_to_sh_tmu(cs);
+
+	return sh_tmu_read(p, TCNT) ^ 0xffffffff;
+}
+
+static int sh_tmu_clocksource_enable(struct clocksource *cs)
+{
+	struct sh_tmu_priv *p = cs_to_sh_tmu(cs);
+	int ret;
+
+	ret = sh_tmu_enable(p);
+	if (ret)
+		return ret;
+
+	/* TODO: calculate good shift from rate and counter bit width */
+	cs->shift = 10;
+	cs->mult = clocksource_hz2mult(p->rate, cs->shift);
+	return 0;
+}
+
+static void sh_tmu_clocksource_disable(struct clocksource *cs)
+{
+	sh_tmu_disable(cs_to_sh_tmu(cs));
+}
+
+static int sh_tmu_register_clocksource(struct sh_tmu_priv *p,
+				       char *name, unsigned long rating)
+{
+	struct clocksource *cs = &p->cs;
+
+	cs->name = name;
+	cs->rating = rating;
+	cs->read = sh_tmu_clocksource_read;
+	cs->enable = sh_tmu_clocksource_enable;
+	cs->disable = sh_tmu_clocksource_disable;
+	cs->mask = CLOCKSOURCE_MASK(32);
+	cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
+	pr_info("sh_tmu: %s used as clock source\n", cs->name);
+	clocksource_register(cs);
+	return 0;
+}
+
+static struct sh_tmu_priv *ced_to_sh_tmu(struct clock_event_device *ced)
+{
+	return container_of(ced, struct sh_tmu_priv, ced);
+}
+
+static void sh_tmu_clock_event_start(struct sh_tmu_priv *p, int periodic)
+{
+	struct clock_event_device *ced = &p->ced;
+
+	sh_tmu_enable(p);
+
+	/* TODO: calculate good shift from rate and counter bit width */
+
+	ced->shift = 32;
+	ced->mult = div_sc(p->rate, NSEC_PER_SEC, ced->shift);
+	ced->max_delta_ns = clockevent_delta2ns(0xffffffff, ced);
+	ced->min_delta_ns = 5000;
+
+	if (periodic) {
+		p->periodic = (p->rate + HZ/2) / HZ;
+		sh_tmu_set_next(p, p->periodic, 1);
+	}
+}
+
+static void sh_tmu_clock_event_mode(enum clock_event_mode mode,
+				    struct clock_event_device *ced)
+{
+	struct sh_tmu_priv *p = ced_to_sh_tmu(ced);
+	int disabled = 0;
+
+	/* deal with old setting first */
+	switch (ced->mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+	case CLOCK_EVT_MODE_ONESHOT:
+		sh_tmu_disable(p);
+		disabled = 1;
+		break;
+	default:
+		break;
+	}
+
+	switch (mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		pr_info("sh_tmu: %s used for periodic clock events\n",
+			ced->name);
+		sh_tmu_clock_event_start(p, 1);
+		break;
+	case CLOCK_EVT_MODE_ONESHOT:
+		pr_info("sh_tmu: %s used for oneshot clock events\n",
+			ced->name);
+		sh_tmu_clock_event_start(p, 0);
+		break;
+	case CLOCK_EVT_MODE_UNUSED:
+		if (!disabled)
+			sh_tmu_disable(p);
+		break;
+	case CLOCK_EVT_MODE_SHUTDOWN:
+	default:
+		break;
+	}
+}
+
+static int sh_tmu_clock_event_next(unsigned long delta,
+				   struct clock_event_device *ced)
+{
+	struct sh_tmu_priv *p = ced_to_sh_tmu(ced);
+
+	BUG_ON(ced->mode != CLOCK_EVT_MODE_ONESHOT);
+
+	/* program new delta value */
+	sh_tmu_set_next(p, delta, 0);
+	return 0;
+}
+
+static void sh_tmu_register_clockevent(struct sh_tmu_priv *p,
+				       char *name, unsigned long rating)
+{
+	struct clock_event_device *ced = &p->ced;
+	int ret;
+
+	memset(ced, 0, sizeof(*ced));
+
+	ced->name = name;
+	ced->features = CLOCK_EVT_FEAT_PERIODIC;
+	ced->features |= CLOCK_EVT_FEAT_ONESHOT;
+	ced->rating = rating;
+	ced->cpumask = cpumask_of(0);
+	ced->set_next_event = sh_tmu_clock_event_next;
+	ced->set_mode = sh_tmu_clock_event_mode;
+
+	ret = setup_irq(p->irqaction.irq, &p->irqaction);
+	if (ret) {
+		pr_err("sh_tmu: failed to request irq %d\n",
+		       p->irqaction.irq);
+		return;
+	}
+
+	pr_info("sh_tmu: %s used for clock events\n", ced->name);
+	clockevents_register_device(ced);
+}
+
+static int sh_tmu_register(struct sh_tmu_priv *p, char *name,
+		    unsigned long clockevent_rating,
+		    unsigned long clocksource_rating)
+{
+	if (clockevent_rating)
+		sh_tmu_register_clockevent(p, name, clockevent_rating);
+	else if (clocksource_rating)
+		sh_tmu_register_clocksource(p, name, clocksource_rating);
+
+	return 0;
+}
+
+static int sh_tmu_setup(struct sh_tmu_priv *p, struct platform_device *pdev)
+{
+	struct sh_tmu_config *cfg = pdev->dev.platform_data;
+	struct resource *res;
+	int irq, ret;
+	ret = -ENXIO;
+
+	memset(p, 0, sizeof(*p));
+	p->pdev = pdev;
+
+	if (!cfg) {
+		dev_err(&p->pdev->dev, "missing platform data\n");
+		goto err0;
+	}
+
+	platform_set_drvdata(pdev, p);
+
+	res = platform_get_resource(p->pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&p->pdev->dev, "failed to get I/O memory\n");
+		goto err0;
+	}
+
+	irq = platform_get_irq(p->pdev, 0);
+	if (irq < 0) {
+		dev_err(&p->pdev->dev, "failed to get irq\n");
+		goto err0;
+	}
+
+	/* map memory, let mapbase point to our channel */
+	p->mapbase = ioremap_nocache(res->start, resource_size(res));
+	if (p->mapbase == NULL) {
+		pr_err("sh_tmu: failed to remap I/O memory\n");
+		goto err0;
+	}
+
+	/* setup data for setup_irq() (too early for request_irq()) */
+	p->irqaction.name = cfg->name;
+	p->irqaction.handler = sh_tmu_interrupt;
+	p->irqaction.dev_id = p;
+	p->irqaction.irq = irq;
+	p->irqaction.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL;
+	p->irqaction.mask = CPU_MASK_NONE;
+
+	/* get hold of clock */
+	p->clk = clk_get(&p->pdev->dev, cfg->clk);
+	if (IS_ERR(p->clk)) {
+		pr_err("sh_tmu: cannot get clock \"%s\"\n", cfg->clk);
+		ret = PTR_ERR(p->clk);
+		goto err1;
+	}
+
+	return sh_tmu_register(p, cfg->name,
+			       cfg->clockevent_rating,
+			       cfg->clocksource_rating);
+ err1:
+	iounmap(p->mapbase);
+ err0:
+	return ret;
+}
+
+static int __devinit sh_tmu_probe(struct platform_device *pdev)
+{
+	struct sh_tmu_priv *p = platform_get_drvdata(pdev);
+	struct sh_tmu_config *cfg = pdev->dev.platform_data;
+	int ret;
+
+	if (p) {
+		pr_info("sh_tmu: %s kept as earlytimer\n", cfg->name);
+		return 0;
+	}
+
+	p = kmalloc(sizeof(*p), GFP_KERNEL);
+	if (p == NULL) {
+		dev_err(&pdev->dev, "failed to allocate driver data\n");
+		return -ENOMEM;
+	}
+
+	ret = sh_tmu_setup(p, pdev);
+	if (ret) {
+		kfree(p);
+		platform_set_drvdata(pdev, NULL);
+	}
+	return ret;
+}
+
+static int __devexit sh_tmu_remove(struct platform_device *pdev)
+{
+	return -EBUSY; /* cannot unregister clockevent and clocksource */
+}
+
+static struct platform_driver sh_tmu_device_driver = {
+	.probe		= sh_tmu_probe,
+	.remove		= __devexit_p(sh_tmu_remove),
+	.driver		= {
+		.name	= "sh_tmu",
+	}
+};
+
+static int __init sh_tmu_init(void)
+{
+	return platform_driver_register(&sh_tmu_device_driver);
+}
+
+static void __exit sh_tmu_exit(void)
+{
+	platform_driver_unregister(&sh_tmu_device_driver);
+}
+
+early_platform_init("earlytimer", &sh_tmu_device_driver);
+module_init(sh_tmu_init);
+module_exit(sh_tmu_exit);
+
+MODULE_AUTHOR("Magnus Damm");
+MODULE_DESCRIPTION("SuperH TMU Timer Driver");
+MODULE_LICENSE("GPL v2");